Some superconductors not only have a zero-resistance effect but also have a Meissner effect. The superconductor may be considered as a perfect diamagnet. Magnetic flux of an external magnetic field can not enter into an interior of the superconductor but are parallel to a surface of the superconductor. A magnetic field direction generated by a superconducting current induced on the surface of the superconductor is just opposite to that of the external magnetic field. The two magnetic fields interact to generate a magnetic thrust. The superconducting rotor can be suspended and rotated, by means of the Meissner effect of the superconductor, and the superconducting rotor may be operated stably without energy loss. Therefore, a variety of precision instruments developed with superconducting characteristics is highly precise and has a quite low energy consumption.
Due to limitations from processing technologies, it is quite difficult to obtain an absolute perfect rotor, and practically there exist various processing variations, which mainly involves two aspects, that is, a mass of the rotor is eccentric and a surface of the rotor is not a perfect sphere. The mass eccentricity of the rotor makes a center of the mass not coincide with a centre of the sphere. Thus, when the rotor rotates about an axis extending through two poles; the rotor is simultaneously subject to a gravity force, an electro-magnetic suspension force, and an inertial centrifugal force, so as to make the rotor rotate eccentrically. As a rotational speed of the rotor is increased, vibration of the rotor is continuously increased, and vibration amplitude thereof is continuously increased. When the rotational speed of the rotor is close to a critical rotational speed, the rotor will generate the strongest vibration, and the amplitude reaches a maximum value. An operating rotational speed of the rotor is generally higher than one-order critical rotational speed of the rotor, and thus it is required for an effective means to inhibit vibration of the rotor during a process that the rotor starts, accelerates, and reaches the operating rotational speed. When vibration of the rotor is relatively strong, due to non-absolute homogeneity nature of the superconducting material, the rotor is accompanied with capturing magnetic flux and alternative current loss under vibration, thereby affecting superconducting diamagnetism of the rotor, so that supporting suspension stability and supporting control precision of the superconducting rotor are decreased. A gap between the superconducting rotor and an inner wall of a rotor cavity is generally quite small. As vibration of the rotor is increased, increment of vibration amplitude and vibration energy may cause the superconducting rotor to transiently lose stability, yielding a phenomenon that the superconducting rotor scrapes against the inner wall of the rotor cavity, and thus scratches are formed on an outer surface of the rotor and the inner wall of the rotor cavity, and thus they can no longer be used. In a serious case, it may be possible for the rotor to fall down after scraping and thus damage the system. Therefore, inhibiting vibration during acceleration and deceleration of the rotor is one of key technologies to be urgently solved in research on operation of the superconducting rotor, and effectively controlling vibration of the rotor is also one of necessary conditions with which the superconducting rotor can operate normally and safely.